Time-Resolved Study of Nanomorphology and Nanomechanic Change of Early-Stage Mineralized Electrospun Poly(lactic acid) Fiber by Scanning Electron Microscopy, Raman Spectroscopy and Atomic Force Microscopy.

Mengmeng Wang,Yin Cai,Bo Zhao,Peizhi Zhu

doi:10.3390/nano7080223

Mengmeng Wang, Yin Cai + Show 2 more

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https://doi.org/10.3390/nano7080223

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Journal: Nanomaterials	Publication Date: Aug 17, 2017
Citations: 4	License type: CC BY 4.0

Affiliation: Yangzhou University, Nanjing Normal University

Abstract

In this study, scanning electron microscopy (SEM), Raman spectroscopy and high-resolution atomic force microscopy (AFM) were used to reveal the early-stage change of nanomorphology and nanomechanical properties of poly(lactic acid) (PLA) fibers in a time-resolved manner during the mineralization process. Electrospun PLA nanofibers were soaked in simulated body fluid (SBF) for different periods of time (0, 1, 3, 5, 7 and 21 days) at 10 °C, much lower than the conventional 37 °C, to simulate the slow biomineralization process. Time-resolved Raman spectroscopy analysis can confirm that apatites were deposited on PLA nanofibers after 21 days of mineralization. However, there is no significant signal change among several Raman spectra before 21 days. SEM images can reveal the mineral deposit on PLA nanofibers during the process of mineralization. In this work, for the first time, time-resolved AFM was used to monitor early-stage nanomorphology and nanomechanical changes of PLA nanofibers. The Surface Roughness and Young’s Modulus of the PLA nanofiber quantitatively increased with the time of mineralization. The electrospun PLA nanofibers with delicate porous structure could mimic the extracellular matrix (ECM) and serve as a model to study the early-stage mineralization. Tested by the mode of PLA nanofibers, we demonstrated that AFM technique could be developed as a potential diagnostic tool to monitor the early onset of pathologic mineralization of soft tissues.

Highlights

Poly(lactic acid) (PLA)-based biomaterials as biodegradable and biocompatible materials are widely used in bone tissue engineering [1,2]
Sodium chloride (NaCl), sodium bicarbonate (NaHCO3), potassium chloride (KCl), Trihydrate potassium hydrogen phosphate (K2HPO4·3H2O), magnesium chloride hexahydrate (MgCl2·6H2O), calcium chloride (CaCl2), sodium sulfate (Na2SO4), Dichloromethane (DCM) and hydrochloric acid (HCl) were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China), Tris(hydroxymethyl)aminomethane (HOCH2)3CNH2 were purchased from Sigma-Aldrich (VETEC, Milwaukee, WI, USA), poly(lactic acid) (PLA) were purchased from NatureWorks (Blair, NE, USA)
After being immersed in simulated body fluid (SBF) for 0–21 days, the morphology of the PLA nanofibers was observed by scanning electron microscopy (SEM)

Summary

Introduction

Poly(lactic acid) (PLA)-based biomaterials as biodegradable and biocompatible materials are widely used in bone tissue engineering [1,2]. The most appealing electrospinning characteristic has been shown to be the mimicking nano-scale fibrous topography of extracellular matrix (ECM) in the tissue engineering field [5,6,7]. This technique allows for the production of polymer fibers with diameters varying from 3 nm to greater than 5 μm, which are capable of supporting a wide variety of cell types [8,9]. Nanofibers produced by electrostatic spinning have been successfully used as scaffold materials for tissue engineering due to their large surface-area-to-volume ratio, high porosity, and delicate microstructure [10,11,12]. The electrospinning process has shown great potential in various applications due to its ability of facile producing high surface-to-volume fibrous structure [13,14,15]

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